Cam cutter



Feb. 10, 1948,

2 Sheets-Sheet 1 Filed June 2, 1945 CW 00 Q0 1 3 a W R t N. 3% 1 b0 W/ W Id 9 a 00m Y T No Q. 5 en W L S or IIQW .fiQ T T QR mLl Pq a I m a ATTORNEY;

Patented Feb. 10, 1948 CAM CUTTER Stephen J. Perez, Rochester, N. Y., assignor of one-half to Joseph M. Murray, Rochester,

Application June 2, 1945, Serial No. 597,355

(o1. sac-13.9)

Claims. 1 This invention relates to profile or contour cutting machinery and particularly to means for controlling the relative disposition of a work piece and a, tool during a machining operation.

The principles of the present invention are not limited to the particular application illustrated and described in detail in the following specification. The particular example shown herein is by way of example. Further, while the apparatus shown and described isin the form of a demountable fixture which may be secured to the work table of a milling machine, drill press, or other machine tool, it'is intended that a complete and unitary machine tool embodying the work holding principles here set forth may be constructed to include the principles of the present invention without the feature of demountability.

Referring to the particular application set forth by way of example, the object is to cut a rotatable cam which is to act upon a follower carried by an oscillating arm having a relatively fixed axis of oscillation. In this particular instance, it is desired that the oscillating arm have a highly precise and constant angular movement for each increment of angular movement of the cam about its own axis of rotation. To this end it is necessary to correct for the error which normally is introduced by reason of the fact that the point of contact or tangency of the cam follower with the cam periphery is not fixed or constant and varies with variations in the angu lar position of the cam follower arm. Another factor of error is due to the harmonic rate of rise ordinarily resulting when a cam follower is carried by a pivoted arm and thus moves through a fixed are.

When the principles of the present invention are pursued these two factors of error are avoided and corrective account is also taken of the fact that the relationship of the axis of the cam and the axis of the cam follower is modified by the fact that the engaging surface of the cam follower is arcuate. In other words, allowance is made for the diameterof the cam follower roller. The latter may be accomplished by merely using a rotating cutter of the same radius as the cam follower to be used.

To adapt the apparatus readily to conventional machine tool construction, it is more efiicient to regard the cutter, which occupies the position of the cam follower in generating the cam, as having a fixed axis. I then proceed to revolve the cam blank along an arc of the same radius as the center to center length of the cam follower supporting arm. This revolution is controlled to occur in predetermined ratio with respect to rotation of the cam blank on its own axis as generation of the cam profile thereof progresses. While specific reference is had herein to milling or other cutters, the principles are applicable'to grinding or other finishing'or surfacing processes.

While various mechanical modifications of the principles of my invention may be made. a single complete embodiment is described in detail and shown in the accompanying drawings, by way of example. However, the scope of my invention is not to be considered limited in any way excepting as defined in the appended claims.

In the drawings:

Fig. 1 is a plan view of work supporting and securing means adapted to be secured to the work holding element or at the work station of a machine tool;

Fig. 2 is a side elevational view thereof;

Fig. 3 is a transverse cross-sectional View approximately on line 3-3 of Fig. 1; and

Fig. 4 is a fragmentary cross-sectional view on line 44 of Fig. 1,

Throughout the several figures of the drawings, like characters of reference denote like parts and the numeral l0 designates a main base plate for securement to a milling machine, drill press, grinder, or other machine tool work table in any desired conventional manner.

The base I 0 has pivotally secured thereto a longitudinal arm II and, as appears best in Fig. 3, a headed pin l2 screws into the base I 0 to establish .a fixed pivot axis for arm ll. Adjacent to the pivoted end of arm II a vertical plate l4 isfixed to an edge thereof as by screws l5, and the plate [4 supports a block I! which extends over arm II but vertically spaced therefrom. Plate 14 has a longitudinal groove 20 and block I 1 is rovided with a tongue 2| for engagement therein. A screw 22 serves to lock the block II in any desired adjusted longitudinal position along the plate M. In the form shown, the upper edge of plate [4 is graduated as shown in Fig. 1 and the manner in which the setting of block I 1 controls the resultant product will presently appear.

The block I l is provided with a vertical work holding spindle 25 which, as shown in Fig. 3, may rotate in a bushing 28. At its upper end spindle 25 has fixed thereto a collar 28 which receives and supports a cam blank 29. In Fig. 1 the collar 28 has been removed for clearness. An

-55 screwed into arm H upper threaded extension 30 of spindle 25 receives a collar 3| and a nut 32 which co-operate to releasably clamp the cam blank to collar 28. To insure against relative rotation between the cam blank and spindle 25 the collar 26 may be fitted with an upwardly projecting dowel pin 34 and the cam blanks willthen be provided with registering openings to receive the dowel pin 34.

The relative position of the axis of spindle '25 and pivot pin I2, as viewed in plan, duplicates the relative positions of the cam axis and the axis of oscillation of the follower roller supporting arm with which the cam is to be used. As viewed in Fig. 3, the spacing of thegaxis of spindle 25 and the axis of pivot pin I2" equals the'radiusof the cam blank at the particular moment of contact plus the radius of the ;cam roller. ,As viewed at right angles to Fig. 3 the spacing of the two axes referredto is equal to the'center to center length of the cam roller arm. This distance is adjustable inthe 'form'i llustrated, .and *in Figf3 -'is shown set for a roller iarm' whi'ch osc'il'lates' the :rollerralong an; arc. of :of ;an inch radius. In .Fig. 3 a :cutter rotatable aabout a relatively "fixed vertical axis is a designated 'A.

.The lower .portion ofz'theispindle 25.has:fixed "thereto a ratchet wheel :31; an'd:;a worm'wheel 38 has free rotation upon spindles25. .The worm wheel '1 38 has pivotedztheretdwa pawl =45 for en- :gagementcwith: ratchet :wheel 31 "and a locking xpawl "4| :is pivoted pto-v the underside of block 1| 7, .;a1s0-1for engagement :with ratchet iwheel 3-1. A

,movement of acamfollowerarm andtheangular .movement .of the cam will represent .a, straight line function. This is accomplished by imparting controlled oscillation to'longitudinal arm I Lduring and incident to rotation of the cam. blank.

';To this end the spindle 25 rotatably supports ,by means of a.screw, see Fig. .5. Arm sup- ..ports a companion-drumt'l for free rotation. A

fiexible'ta-pe or band 52 is wound partially about each of the -drums'5ll and 5| and a third drum 54 ;is fixedco-axially with drum5l. As shown in Fig. 4,;the-drums 5| and '54 may be integrally formed and-rotatably' mounted upon a pivot pin Ablock 58 is removably "fixed to the base i0 andhas 'an arcuate vertical face 59, which is of=the same radius as the distance from pivotpin-l2 to a point of tangency with the periphery-of drum 54, minus the thickness of a-tape or band -65 whichextends about drum 54 and is fixed to block 58 at its other end as-indicated at 62 in Fig. 1.

A compression coil spring65 has one of its ends :anchored to .a blockxfit fixed to base I .and its -other end engages against the outer end oflongi- :tudinal arm II to .urge theilatterin 1a:.counter- .iclockwise.;direction:about the :pivot pin :12. A

=-'52 to give equal clockwise rotation to drums 5| land 54. The band 60 thus winds upon drum 54 and moves the center of drums 5| and 54 up- '-wardly'as viewedjn Fig. 1 along an arc struck "from the axis'of *pivot pin I2. This movement exactly reproduces the relative changing movezmentsandcenter distances of the cam blank and the cam follower and the resultant cam profile-is accordingly exactly formed to impart constant angular movement to the cam follower of the supporting arm for.-.each increment of angular movement of. therresultant. cam.

.Assuming, for example, that eightduplicate rises are to beformed ona cam blank,.the operator will:rotate handledfi-untillockin pawl 4| v.dropsinto the nextrecess inlratchet Wheel .31. The operator then reversesthe rotationof handle :46 which produces .free reverserotation of worm wheel 38 and drum 50 .until pawl .40 picks .up another tooth of. ratchet .wheel 31 whereupon the next successive ,camrisemay. be formed. Note that thereverse rotation .ofworm Wheel"38-w.ith .drum..5ll relocates thev cam blank axis to begin .another .rise formation without .rotation of .the -camblank on itsown axis.

Thedistance (from the center .of .pivot 'pin i2 to arcuate surface 59 determines the height .of the rise formedon. the cam, other'things'being equal. The block 58 is held in.,a slot "|2,in base W ,by a bolt 13. Other blocksmay be substituted .at .dilferent radii from pivot'pin" I2 and'the drums 5| and .54 may be relocated:.to"produce'camspf other rise dimensions.

What is claimed is:

1. Apparatus for generating the profile of 'a cam adapted to act upon an arcuately movable .follower and move it at a-relative1y constant angular rate, said apparatus "comprising a rotating forming tool having a relatively fixed'axis, a work holding element supported for pivotal movement about an axisparallel to the tool axis and spaced therefrom a distance equal'to the desired radius of movement of the cam follower, a work holding spindle journaled in said work holding element with its axis parallel to the pivot axis of the work holding element and spaced therefrom the same distance as the desired spacing of the cam-axis-and' the-axis of arcuate movementof the-follower, and drive means between said work holding element and said spindle whereby their relative angular rates of rotation are constant during generation of the cam profile.

2. A work. holding'fixture f or" co -iop oration with :a rotating: formingitool having a'relatively fixed :axis, said rfixture comprising :;a base and a work holding elementtpivoted-thereto on-an axis parallel to the axis of the forming. tool, azwork holding spindle ccarried by said work holding element '-with 'its'axis parallel to; saidrfixedaxis and said pivot axis and means for rotating said spindle 'to rotate a workipiecein engagement with said :iorming'tool, and :drive means connecting said :spindle and :said work holding -..element whereby the-latter is;rotated;.about its pivotal connection '5 with the base at a constant relative angular rate of rotation with respect to the rate of rotation of said spindle during a forming operation.

3. Apparatus for generating the profile of a cam adapted to act upon an arcuately movable follower and move it at a relatively constant angular rate, said apparatus comprising a rotating forming tool element and a work holding element, one of said elements being supported for pivotal movement about an axis parallel to the axis of rotation of the forming tool and spaced therefrom a distance equal to the desired radius of the arcuate path of the cam follower, a work holding spindle journaled in said work holding element with its axis parallel to the pivot axis of the one of said elements and spaced there from the same distance as the desired spacing of the cam axis and the axis of arcuate movement of the follower, and drive means between the one of said elements and said spindle whereby their relative angular rates of rotation are constant during generation of the cam profile.

4. Apparatus for generating a profile on a work piece comprising a rotating forming tool element and a work holding element, one of said elements being supported for pivotal movement about an axis parallel to the axis of rotation of the forming tool and spaced therefrom a predetermined distance, a work holding spindle journaled in said work holding element with its axis parallel to the pivot axis of the one of said elements and spaced therefrom, and drive means between the one of said elements and said spindle whereby their relative angular rates of rotation are constant during generation of the profile or the workpiece.

5. Apparatus for generating the profile of a work piece comprising a rotating forming tool element and a work holding element, one of said elements being supported for pivotal movement about an axis parallel to the tool axis, a work holding spindle journaled in said work holding element with its axis parallel to the pivot axis of the one of said elements and spaced therefrom, rotary drive means coaxially fixed with respect to the one of said elements and rotary drive means coaxial and engageable with said spindle, and transmission means between said two drive means whereby the relative angular rates of rotation of the one of said elements and said spindle are constant during generation of the profile of the workpiece,

STEPHEN J. PEREZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 935,345 Wiebke Sept. 28, 1909 1,003,816 Scoville Sept. 19, 1911 1,575,713 Olson Mar. 9, 1926 1,651,432 Bath Dec. 6, 1927 1,689,370 Tessky Oct. 30, 1928 1,704,833 Irwin Mar. 12, 1929 2,116,686 Odom May 10, 1938 2,144,771 Mossdorf Jan. 24, 1939 2,386,973 Mieth Oct. 16, 1945 V FOREIGN PATENTS Number Country Date 434,154 Germany Sept. 22, 1926 579,272 Germany June 22, 1933 

